A very fun puzzle Game! I liked how it started with the book explanations and in general the lore is an creative idea :D
The heart sign was a nice easter egg. I like it when platformer hide stuff, even ifs not necessary to advance. :D
The score goal being to use as less ghosts as possibly is cool, but i would have liked to have seen how my total score was too, to keep track of it.
I sadly couldnt continue on one of the puzzles, because i kept on bugging into the walls. It was this one:
I also tried a lot of combinations with purple and orange, to stay small but still bugged into the ceiling and respawned then. Oh and dashing into walls made me bug into them too sometimes.
I dont know if it helps but: i got the bug in fullscreen and windowed mode and im playing on microsoft edge.
But i still enjoyed the other levels and how they teach different combinations in a playful way :D